Wound healing system using positive pressure to promote granulation at a tissue site

ABSTRACT

A wound healing system for promoting healing of a wound of a patient includes a positive pressure source, a reduced pressure source, and a porous foam positioned in contact with the wound. The porous foam includes a plurality of flow channels in fluid communication with the reduced pressure source. The system further includes a filler member having a flexible wall defining an interior chamber. The interior chamber is in fluid communication with the positive pressure source, and a cover member is positioned over the filler member.

RELATED APPLICATIONS

The present invention claims the benefit, under 35 U.S.C §119(e), of thefiling of U.S. Provisional Patent Application Ser. No. 61/489,786,entitled “Wound Healing System Using Positive Pressure to PromoteGranulation at a Tissue Site,” filed May 25, 2011, which is incorporatedherein by reference for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to reduced pressure treatmentsystems and more particularly to a wound healing system for promotinggranulation at a tissue site by delivery of reduced pressure andpositive pressure.

2. Description of Related Art

Clinical studies and practice have shown that providing a reducedpressure in proximity to a tissue site augments and accelerates thegrowth of new tissue at the tissue site. The applications of thisphenomenon are numerous, but one particular application of reducedpressure involves treating wounds. This treatment (frequently referredto in the medical community as “negative pressure wound therapy,”“reduced pressure therapy,” or “vacuum therapy”) provides a number ofbenefits, including migration of epithelial and subcutaneous tissues,improved blood flow, and micro-deformation of tissue at the wound site.Together these benefits result in increased development of granulationtissue and faster healing times. Typically, reduced pressure is appliedby a reduced pressure source to tissue through a porous pad or othermanifold device. The porous pad contains cells or pores that are capableof distributing reduced pressure to the tissue and channeling fluidsthat are drawn from the tissue. The porous pad often is incorporatedinto a dressing having other components that facilitate treatment.

SUMMARY

The problems presented by existing reduced pressure treatment systemsare solved by the systems and methods of the illustrative embodimentsdescribed herein. In one illustrative embodiment, a wound healing systemfor promoting healing of a wound of a patient is provided. The systemincludes a positive pressure source, a reduced pressure source, and aporous foam positioned in contact with the wound. The porous foamincludes a plurality of flow channels in fluid communication with thereduced pressure source. The system further includes a filler memberhaving a flexible wall defining an interior chamber. The interiorchamber is in fluid communication with the positive pressure source, anda cover member is positioned over the filler member.

In another embodiment, a wound healing system for promoting healing of awound includes a positive pressure source, a reduced pressure source,and a filler member having an expandable wall defining an interiorchamber. The interior chamber is in fluid communication with thepositive pressure source, and a cover member is positioned over thefiller member to secure the filler member at the wound. The cover membercreates a sealed space capable of maintaining a reduced pressure, andthe sealed spaced is in fluid communication with the reduced pressuresource. In this embodiment, external fluids are not supplied to thewound.

In still another embodiment, a wound healing system for promotinghealing of a wound of a patient includes a pump having an inlet and anexhaust. The inlet of the pump has a reduced pressure that is less thana reference pressure, and the exhaust has a positive pressure that isgreater than the reference pressure. The system further includes agranulation-promoting material positioned at the wound and fluidlyconnected to the inlet of the pump. A filler member having an interiorchamber is fluidly connected to the exhaust of the pump, and a covermember is positioned over the filler member to secure the filler memberat the wound.

In yet another embodiment, a wound healing system for promoting healingof a wound of a patient includes a reduced pressure source and a fillermember having a plurality of sealed compartments. Each of the sealedcompartments includes a fluid at a pressure that is greater than orequal to an ambient pressure surrounding the sealed compartments. Acover member is positioned over the filler member to secure the fillermember at the wound, the cover member creating a sealed space capable ofmaintaining a reduced pressure. The sealed spaced is in fluidcommunication with the reduced pressure source. The cover memberprovides a biasing force to the filler member directed toward the wound.

Other objects, features, and advantages of the illustrative embodimentswill become apparent with reference to the drawings and detaileddescription that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a partially cross-sectional, perspective view of atissue treatment system according to an illustrative embodiment;

FIG. 2 illustrates a fluid flow schematic for an embodiment of thetissue treatment system of FIG. 1;

FIGS. 3A and 3B illustrate a partially cross-sectional, perspective viewof a tissue treatment system according to an illustrative embodiment;

FIG. 4 illustrates a partially cross-sectional, perspective view of atissue treatment system according to an illustrative embodiment;

FIG. 5 illustrates a partially cross-sectional, perspective view of atissue treatment system according to an illustrative embodiment;

FIG. 6 illustrates a partially cross-sectional, perspective view of atissue treatment system according to an illustrative embodiment;

FIG. 7 illustrates a partially cross-sectional, perspective view of atissue treatment system according to an illustrative embodiment;

FIG. 8 illustrates a partially cross-sectional, perspective view of atissue treatment system according to an illustrative embodiment, thetissue treatment system having a pre-inflated filler member;

FIG. 9 illustrates a perspective view of the pre-inflated filler memberof FIG. 8; and

FIG. 10 illustrates a cross-sectional side view of the pre-inflatedfiller member of FIG. 9 taken at 10-10.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the following detailed description of several illustrativeembodiments, reference is made to the accompanying drawings that form apart hereof, and in which is shown by way of illustration specificpreferred embodiments in which the invention may be practiced. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the invention, and it is understood that otherembodiments may be utilized and that logical structural, mechanical,electrical, and chemical changes may be made without departing from thespirit or scope of the invention. To avoid detail not necessary toenable those skilled in the art to practice the embodiments describedherein, the description may omit certain information known to thoseskilled in the art. The following detailed description is, therefore,not to be taken in a limiting sense, and the scope of the illustrativeembodiments are defined only by the appended claims. Unless otherwiseindicated, as used herein, “or” does not require mutual exclusivity.

The term “reduced pressure” as used herein generally refers to apressure less than the ambient pressure at a tissue site that is beingsubjected to treatment. In most cases, this reduced pressure will beless than the atmospheric pressure at which the patient is located.Alternatively, the reduced pressure may be less than a hydrostaticpressure associated with tissue at the tissue site. Although the terms“vacuum” and “negative pressure” may be used to describe the pressureapplied to the tissue site, the actual pressure reduction applied to thetissue site may be significantly less than the pressure reductionnormally associated with a complete vacuum. Reduced pressure mayinitially generate fluid flow in the area of the tissue site. As thehydrostatic pressure around the tissue site approaches the desiredreduced pressure, the flow may subside, and the reduced pressure is thenmaintained. Unless otherwise indicated, values of pressure stated hereinare gauge pressures. Similarly, references to increases in reducedpressure typically refer to a decrease in absolute pressure, whiledecreases in reduced pressure typically refer to an increase in absolutepressure.

The term “positive pressure” as used herein generally refers to apressure greater than the ambient pressure at a tissue site that isbeing subjected to treatment. In some cases, this positive pressure willbe greater than the atmospheric pressure at which the patient islocated. Alternatively, the positive pressure may be greater than ahydrostatic pressure associated with tissue at the tissue site.

The tissue treatment systems and methods described in this applicationimprove the treatment of a tissue site by increasing or improvinggranulation tissue development, thus allowing healing of a wound thatmay not otherwise heal with traditional treatment modalities, or in somecases, allowing an increased rate in healing of a wound. Granulation maybe promoted by exposing the tissue site to micro-mechanical stresses andstrains. While the creation of micro-mechanical stresses and strains ata tissue site may be provided by applying a reduced pressure to a sealedspace adjacent the tissue site, the system and methods described hereinemploy the use of positive pressure or forces to create such stressesand strains. Use of positive pressure or forces can decrease the amountof reduced pressure that is applied to a tissue site to remove fluidsand exudate from the tissue site. In some cases, use of a positivepressure or forces may eliminate the need for reduced pressure entirely,especially when absorbent materials or other fluid-removal materials ormechanisms are employed.

Referring to FIG. 1, an illustrative embodiment of a tissue treatmentsystem 100 for treating a tissue site 101 on a patient includes adressing 102 placed proximate to the tissue site 101 and a therapy unit104 fluidly coupled to the dressing 102. As used herein, the term“tissue site” may refer to a wound, such as a wound 105, or defectlocated on or within any tissue, including but not limited to, bonetissue, adipose tissue, muscle tissue, neural tissue, dermal tissue,vascular tissue, connective tissue, cartilage, tendons, or ligaments.The term “tissue site” may further refer to areas of any tissue that arenot necessarily wounded or defective, but are instead areas in which itis desired to add or promote the growth of additional tissue. Forexample, reduced pressure tissue treatment may be used in certain tissueareas to grow additional tissue that may be harvested and transplantedto another tissue location.

The dressing 102 is configured to promote the growth of new tissue atthe tissue site 101 and includes a wound healing apparatus 106positioned adjacent to or, in some embodiments, in contact with thetissue site 101. The dressing 102 may further include a cover or drape110 positioned over the wound healing apparatus 106 to secure the woundhealing apparatus 106 at the tissue site 101 and to seal a space that islocated beneath the cover and is at least partially occupied by thewound healing apparatus 106. In one embodiment, the drape 110 extendsbeyond a perimeter of the tissue site 101 and is placed either incontact with or otherwise in proximity to a patient's epidermis 113 tocreate a fluid seal between the drape 110 and the epidermis 113. Thedrape 110 may include an adhesive 115 or bonding agent to secure thedrape 110 to the epidermis 113. In one embodiment, the adhesive 115 maybe used to create a seal between the drape 110 and the epidermis 113 toprevent leakage of reduced pressure from the tissue site 101. In anotherembodiment, a seal layer (not shown) such as, for example, a hydrogel orother material may be disposed between the drape 110 and the epidermis113 to augment or substitute for the sealing properties of the adhesive115. As used herein, “fluid seal” means a seal adequate to maintainreduced pressure at a desired site given the particular reduced pressuresource involved and the particular treatment desired. In one embodiment,the drape 110 and the bonding characteristics of the drape 110 providesealing sufficient to prevent leakage greater than 0.5 L/min at 125 mmHgreduced pressure.

The wound healing apparatus 106 may include a manifold 121 and a fillermember 125. The term “manifold” as used herein generally refers to asubstance or structure that is provided to assist in applying reducedpressure to, delivering fluids to, or removing fluids from the tissuesite 101. The manifold typically includes a plurality of flow channelsor pathways that distribute fluids provided to and removed from thetissue site around the manifold. In one illustrative embodiment, theflow channels or pathways are interconnected to improve distribution offluids provided or removed from the tissue site 101. Examples ofmanifolds may include, for example, without limitation, devices thathave structural elements arranged to form flow channels, such as, forexample, cellular foam, open-cell foam, porous tissue collections,liquids, gels, and foams that include, or cure to include, flowchannels. In one embodiment, the wound healing apparatus 106 includes aporous foam and having a plurality of interconnected cells or pores thatact as flow channels. The porous foam may be a polyurethane, open-cell,reticulated foam such as GranuFoam® material manufactured by KineticConcepts, Incorporated of San Antonio, Tex.

The filler member 125 of the reduced pressure apparatus 106 may beprovided to occupy additional space or volume between the tissue site101 and the cover 110 and may also be provided to better facilitate theapplication of a positive force to the tissue site 106 in order toencourage granulation and new tissue growth. The filler member 125 mayin some embodiments be an inflatable bladder or balloon that isexpandable when injected or otherwise filled with a fluid. In otherembodiments, the filler member 125 may be a pre-filled bladder or othercontainer that is positioned between the tissue site 106 and the cover110. Several examples of filler members 125 are provided herein.

The manifold 121 and filler member 125 may work together to encouragetissue growth in the presence of a positive force or pressure. Inone-embodiment, the manifold 121 may include at least onegranulation-promoting surface 127 that is capable of contacting thetissue site 101. The granulation-promoting surface 127 is capable ofinducing micro-stresses and micro-strain at the tissue site 101 when thegranulation-promoting surface 127 contacts the tissue site 101. Forexample, if the manifold 121 is a reticulated porous foam that includesa plurality of interconnected cells formed by struts or cell walls, thestruts of the reticulated foam may be capable of inducing micro-stressesand micro-strains when the struts are pressed against or into thetissue. By sealing the manifold 121 and filler member 125 proximate thetissue site 101 with the cover 110, expansion of the filler member 125within the sealed space beneath the cover 110 directs a force on themanifold 121 at least in the direction of the tissue site 101. Thisforce is capable of generating the required micro-stresses andmicro-strains where the tissue contacts the granulation-promotingsurface 127.

In FIG. 1, the filler member 125 is embedded within the manifold suchthat the manifold completely surrounds the filler member 125. Asdescribed in more detail below, other arrangements of manifolds andfiller members may be used, and many variations of both the manifold andfiller member are possible. In one embodiment, the manifold may beomitted and the filler member alone positioned within the sealed spacebeneath the cover. In this embodiment, the filler member may include agranulation-promoting surface that is placed in contact with the tissuesite. The granulation-promoting surface may includes projections,protrusions, or a substantially-rough profile to induce micro-stressesand micro-strains at the tissue site. In still other embodiments, thefiller member may be omitted and simply a manifold or othergranulation-inducing substrate may be placed beneath the cover. In thisembodiment, a force on the manifold or granulation-inducing substratemay create the desired micro-strain to induce granulation at the tissuesite.

Referring still to FIG. 1, the dressing 102 further may include apressure interface 133 fluidly coupled to the wound healing apparatus106 and the cover 110. In one embodiment, the interface 133 may bepositioned adjacent to or coupled to the cover 110 to provide fluidaccess to the wound healing apparatus 106. The drape 110 includes anaperture 135 for providing fluid access to the interface 133. A conduit137 fluidly couples the therapy unit 104 and the interface 133. Theinterface 133 is capable of allowing reduced pressure to be delivered tothe tissue site 101 when it is desired to remove fluid from the tissuesite 101 under the influence of reduced pressure. The interface 133 mayalso be fluidly coupled to the filler member 125 through a fillerconduit 141. Fluid connection between the interface 133 and the fillermember 125 allows a fluid (i.e. a gas or liquid) to be delivered to thefiller member 125 under positive pressure such that the filler member125 may be inflated or expanded.

In one embodiment, the therapy unit 104 includes a fluid containmentmember 145 in fluid communication with a reduced pressure source 151. Inthe embodiment illustrated in FIG. 1, the fluid containment member 145is a collection canister that includes a chamber for collecting fluidsfrom the tissue site 101. The fluid containment member 145 alternativelycould be an absorbent material or any other container, device, ormaterial that is capable of collecting fluid.

A separate positive pressure source 153 may be housed within the therapyunit 104. Alternatively, a singe vacuum pump may be disposed within thetherapy unit 104 such that an inlet of the vacuum pump serves as thereduced pressure source 151 and an outlet of the vacuum pump serves asthe positive pressure source 153. The conduit 137 may be a multi-lumentube that is capable of providing one or more conduits to deliverreduced pressure to the dressing 102 and one or more conduits to deliverpositive pressure to the dressing 102. Liquids or exudates communicatedfrom the wound healing apparatus 106 through the conduit 137 are removedfrom the conduit 137 and retained within the collection canister 145.Additional information regarding the transfer of fluids between thedressing and the therapy unit is provided below with reference to FIG.2.

Referring still to FIG. 1, the reduced pressure source 151 and positivepressure source 153 may be one or more electrically-driven vacuum pumps.In another implementation, the reduced and positive pressure sources151, 153 may instead be one or more manually-actuated ormanually—charged pumps that do not require electrical power. In oneembodiment, the reduced pressure and positive pressure sources 151, 153may be one or more piezoelectric-actuated micropumps that may bepositioned remotely from the dressing 102, or at the dressing beneath oradjacent to the cover 110. The reduced and positive pressure sources151, 153 instead may be any other type of pump, or alternatively a wallsuction port or air delivery port such as those available in hospitalsand other medical facilities. The reduced and positive pressure sources151, 153 may be housed within or used in conjunction with the therapyunit 104, which may also contain sensors, processing units, alarmindicators, memory, databases, software, display units, and userinterfaces 161 that further facilitate the application of reducedpressure treatment to the tissue site 101. In one example,pressure-detection sensors (not shown) may be disposed at or near thereduced and positive pressure sources 151, 153. The pressure-detectionsensors may receive pressure data from the interface 133 via lumens inthe conduit 137 that are dedicated to delivering reduced pressure datato the pressure-detection sensors. The pressure-detection sensors maycommunicate with a processing unit that monitors and controls thereduced pressure and positive pressure that is delivered by the reducedand positive pressure sources 151, 153.

Referring to FIG. 2, a fluid flow schematic is depicted for anembodiment of the tissue treatment system 100. Dashed lines betweensystem components in FIG. 2 represent the flow of fluids between thosecomponents. Solid lines represent physical connections or proximitiesthat may exist between the components. As depicted in FIG. 2, thepositive pressure source 153 provides a fluid such as a gas or a liquidto the filler member 125. The direction of fluid flow is from thepositive pressure source 153 to the filler member 125. The positivepressure source 153 may be physically (and fluidly) connected to thefiller member 125 by a conduit such as conduit 137 (see FIG. 1), oralternatively the positive pressure source 153 may include an outletdirectly coupled to the filler member 125. In one embodiment, thepositive pressure source 153 may be a micropump such as apiezoelectric-actuated pump that is disposed adjacent to the fillermember 125. The filler member 125 is operably associated with agranulation-promoting member 165 that may be placed adjacent to or incontact with the tissue site 101. The granulation-promoting member maybe a manifold such as manifold 121, a granulation-promoting surface onthe filler member 125, or any other type of material or substrate thatis capable of promoting granulation tissue growth.

The reduced pressure source 151 provides reduced pressure by drawing orpulling a fluid such as a gas or a liquid toward the reduced pressuresource 151. In one embodiment, the reduced pressure source 151 isphysically (and fluidly) connected to the fluid containment member 145and draws fluid from the fluid containment member 145. The reducedpressure created at the reduced pressure source 151 and the fluidcontainment member 145 is capable of drawing fluid from a fluid space171 adjacent the tissue site 101. It should be understood that the fluidspace 171 may be occupied by the manifold 121 to better distributereduced pressure within the fluid space 171 and at the tissue site 101,thereby resulting in more efficient removal of the fluid.

Referring to FIGS. 3A and 3B, an illustrative embodiment of a tissuetreatment system 300 for treating a tissue site 301 on a patientincludes a dressing 302 placed proximate to the tissue site 301 and atherapy unit 104 fluidly coupled to the dressing 302. Tissue treatmentsystem 300 is similar to tissue treatment system 100 and includes manycomponents that are the same as or similar to those in tissue treatmentsystem 100. Tissue treatment system 300 illustrates a filler member 325that is fully inflated with a fluid. The filler member 125 is embeddedwithin a manifold 321 that includes at least one granulation-promotingsurface 327 that is brought into contact with the tissue site 301 by theinflation of the filler member 325. The filler member 325 and manifold321 are constrained by a cover 310 secured to an epidermis 313 of thepatient such that biasing forces may be applied to the tissue site 301by the granulation-promoting surface 327. While the cover 310 may besubstantially inelastic such that the cover 310 acts as a substantiallyrigid constraint, the cover 310 may instead by elastic, thereby allowingsome expansion of the dressing above the epidermis 313 of the patientthat surrounds the tissue site 301 (as shown in FIGS. 3A and 3B). Thecover 310 creates a sealed space 328 beneath the cover 310 in which themanifold 321 and the filler member 325 reside.

In one embodiment, an inner space of the filler member 325 is fluidlycoupled to a positive pressure source 353, while a reduced pressuresource 351 is fluid coupled to the manifold 321. In the embodimentillustrated in FIG. 3A, the positive pressure source 353 and the reducedpressure source 351 are each separate pumps. In FIG. 3B, the positivepressure source 353 and the reduced pressure source 351 are the samepump, the pump providing reduced pressure to the manifold 321 through aninlet of the pump and positive pressure to the filler member 325 throughthe outlet of the pump. While pumps are illustrated as being thepositive pressure source 353 and reduced pressure source 351 in FIGS. 3Aand 3B, it should be noted that the positive and reduced pressuresources 353, 351 may be any source of positive or negative fluid flow asdescribed previously with respect to positive pressure source 153 andreduced pressure source 151.

In the embodiments illustrated in FIGS. 3A and 3B, fluids are exchangedwith the manifold 321 and the filler member 325 through conduits 383,385. Conduit 383 permits the application of reduced pressure and thusthe removal of fluids from the manifold 321 or the space 328 surroundingthe filler member 325. Conduit 385 permits the application of positivepressure and thus the delivery of fluids to the filler member 325.Conduits 383, 385 may be any type of tube or other fluid conveyingdevice. As illustrated in FIGS. 3A and 3B, conduits 383, 385 may bepositioned through the cover 310. In this embodiment, it is preferredthat an aperture in the cover 310 though which each conduit 383, 385 isplaced be sealed around the conduit 383, 385, either using a sealant orother adhesive, or using a drape material that may be adhered to boththe cover 310 and the conduit 383, 385. Alternatively, the conduits 383,385 may be inserted beneath the cover 310 near an edge of the cover 310where the cover 310 is adhered to the patient's epidermis 313. Again,sealing of the cover 310 around the conduit 383, 385 entry point isimportant, both to maintain the ability of the cover 310 to secure thefiller member 325 and the manifold 321 at the tissue site 301 and toallow the cover 310 to maintain a reduced pressure within the manifold321 or the space 328 between the filler member 325 and the tissue site301. Similarly, it is important for conduit 385 to be properly sealed tothe filler member 325. Proper sealing of the conduit 385 preventspositively-pressurized fluid from the conduit 385 from leaking into themanifold 325 or the space 328 between the filler member 325 and thetissue site 301. While the conduits 383, 385 have been described aspassing through or underneath the cover 310, the conduits 383, 385instead could be connected to an interface similar to interface 133associated with FIG. 1. The interface would allow sealed passage offluid carried by the conduits 383, 385 through the cover 310.

A canister 345 may be fluidly coupled between the dressing 302 and thereduced pressure source 351. The canister 345 is capable of collectingfluids (especially liquids) drawn from the tissue site 301 by thereduced pressure source 351.

Referring to FIG. 4, an illustrative embodiment of a tissue treatmentsystem 400 for treating a tissue site 401 on a patient includes adressing 402 placed proximate to the tissue site 401 and a therapy unit404 fluidly coupled to the dressing 402. Tissue treatment system 400 issimilar to tissue treatment systems 100, 300 and includes manycomponents that are the same as or similar to those in tissue treatmentsystems 100, 300.

Tissue treatment system 400 includes a filler member 425 that isinflated with a fluid. Positioned beneath the filler member 425 is amanifold 421 that includes at least one granulation-promoting surface427 that is brought into contact with the tissue site 401 by theinflation of the filler member 425. An absorbent layer 429 is positionedabove the filler member 425 and in fluid communication with the manifold421. The absorbent layer 429, filler member 425, and manifold 421 areconstrained by a cover 410 secured to an epidermis 413 of the patient.The attachment of the cover 410 over the layers of the dressing 402allows biasing forces to be applied to the tissue site 401 by thegranulation-promoting surface 427. While the cover 410 may besubstantially inelastic such that the cover 410 acts as a substantiallyrigid constraint, the cover 410 instead may be elastic, thereby allowingsome expansion of the dressing above or below the epidermis 413 of thepatient that surrounds the tissue site 401.

In one embodiment, an inner space of the filler member 425 is fluidlycoupled to a positive pressure source 453, while a reduced pressuresource 451 is fluid coupled to the absorbent layer 429 and the manifold421. In the embodiment illustrated in FIG. 4, the function of thepositive pressure source 453 and the reduced pressure source 451 areprovided by a single pump. Reduced pressure is provided by an inlet 454of the pump and is regulated by a regulating valve 456. Positivepressure is provided by an outlet 458 of the pump and is regulated by aregulating valve 460. While a single pump is illustrated as providingboth positive and negative pressure, it should be noted that thepositive and reduced pressures may be supplied by separate pumps or byany other source of positive or negative fluid flow.

The fluid connection between the reduced pressure source 451 and theabsorbent layer 429 assists in drawing liquids from the manifold 421into the absorbent layer 429 for storage. The absorbent layer 451 may beformed from an absorbent, adsorbent, desiccant, or any other type ofmaterial that is capable of capturing or storing liquid from the tissuesite 401. Examples of materials from which the absorbent layer may beconstructed include, without limitation, BASF's Luquafleece material,superabsorbent-fibre-based non-woven materials such as that offered byTechnical Absorbents, hydrophylic foams such as that offered by FoamPartners HME, high-wicking fibre-based materials such as that offered byFiltrona, and hydrophylic sintered polymers such as that offered byPoryair.

As illustrated in FIG. 4, the application of reduced pressure throughthe absorbent layer 429 and manifold 421 may result in the dressing 402being compressed such that cover 410 is pulled below the epidermis 413of the patient that surrounds the tissue site 401. While thiscompression of the dressing 402 assists in applying a biasing force,represented by arrows 472, to the tissue site 401, the biasing force maybe increased by the presence of the filler member 425 beneath the cover410. The inflation of the filler member 425 beneath the cover 410results in less reduced pressure being needed to encourage granulation.Instead, reduced pressure can be provided primarily to remove fluid fromthe tissue site 401.

Referring to FIG. 5, an illustrative embodiment of a tissue treatmentsystem 500 for treating a tissue site 501 on a patient includes adressing 502 placed proximate to the tissue site 501 and a therapy unit504 fluidly coupled to the dressing 502. Tissue treatment system 500 issimilar to tissue treatment systems 100, 300, 400 and includes manycomponents that are the same as or similar to those in tissue treatmentsystems 100, 300, 400.

Tissue treatment system 500 includes a filler member 525 that isinflated with a fluid. The filler member 525 is embedded within amanifold 521 that includes at least one granulation-promoting surface527 that is brought into contact with the tissue site 501 by theinflation of the filler member 525. The filler member 525 and manifold521 are constrained by a cover 510 secured to an epidermis 513 of thepatient such that biasing forces may be applied to the tissue site 501by the granulation-promoting surface 527. The cover 510 creates a sealedspace 528 beneath the cover 510 in which the manifold 521 and fillermember 525 reside. While the cover 510 may be substantially inelasticsuch that the cover 510 acts as a substantially rigid constraint, thecover 510 instead may be elastic, thereby allowing some expansion of thedressing above or below the epidermis 513 of the patient that surroundsthe tissue site 501.

A fluid containment member 545 is positioned in fluid communication withthe manifold 521 and the space 528 beneath the cover 510. In oneembodiment, the fluid containment member 545 is a fluid pouch thatincludes an absorbent 529 similar to other absorbents described herein.The fluid containment member 545 may be positioned above the cover 510outside of the sealed space 528. Alternatively, the fluid containmentmember 545 may be positioned beneath the cover, and in one embodimentfluid containment member 545, or the absorbent 529 therein, may be indirect contact with the manifold 521.

In the embodiment illustrated in FIG. 5, an inner space of the fillermember 525 is fluidly coupled to a positive pressure source 553. Thepressure of fluid provided by the positive pressure source 553 isregulated by a regulating valve 560. No reduced pressure source isprovided in the embodiment illustrated in FIG. 5. Instead fluid removalfrom the tissue site 501 is provided by the fluid containment member545. As the manifold 521 becomes filled with fluid, the absorbent 529 inthe fluid containment member 545 assists in drawing the fluid from themanifold 521 and into the fluid containment member 545 for storage. Themovement of the fluid is further aided by the inflation of the fillermember 525, which decreases the volume of the space 528 occupied by themanifold 521 and thus the fluid.

While no reduced pressure source is illustrated in FIG. 5, it isimportant to note that a reduced pressure source may be fluidlyconnected to the fluid containment member 545 to provide active drainageof the space 528 and the tissue site 501. Such a reduced pressure sourcemay be similar to the other reduced pressure sources described herein.

In FIG. 5, the fluid containment member 545 is fluidly connected to themanifold 521 by a pressure interface 533 positioned adjacent to orcoupled to the cover 510. The cover 510 includes an aperture 535 throughwhich the pressure interface 533 passes. A conduit 537 fluidly couplesthe therapy unit 504 (and positive pressure source 553) to the interface533. Fluid connection between the interface 533 and the filler member525 allows a fluid (i.e. a gas or liquid) to be delivered to the fillermember 525 under positive pressure such that the filler member 525 maybe inflated or expanded.

As illustrated in FIG. 5, the filling of the filler member 525 in theabsence of reduced pressure to the space 528 may result in the dressing502 expanding above the epidermis 513 of the patient that surrounds thetissue site 501. This expansion of the dressing 502 assists in applyinga biasing force, represented by arrows 572, to the tissue site 501. Theinflation of the filler member 525 beneath the cover 510 results in noreduced pressure being needed to encourage granulation. In thisparticular embodiment, fluid is removed from the dressing 502 withoutreduced pressure as well.

Referring to FIG. 6, an illustrative embodiment of a tissue treatmentsystem 600 for treating a tissue site 601 on a patient includes adressing 602 placed proximate to the tissue site 601 and a therapy unit604 fluidly coupled to the dressing 602. Tissue treatment system 600 issimilar to tissue treatment systems 100, 300, 400, 500 and includes manycomponents that are the same as or similar to those in tissue treatmentsystems 100, 300, 400, 500.

Tissue treatment system 600 includes a filler member 625 that isinflated with a fluid. Positioned beneath the filler member 625 is amanifold 621 that includes at least one granulation-promoting surface627 that is brought into contact with the tissue site 601 by theinflation of the filler member 625. The filler member 625 and manifold621 are constrained by a cover 610 secured to an epidermis 613 of thepatient such that biasing forces may be applied to the tissue site 601by the granulation-promoting surface 627. The cover creates a sealedspace 628 beneath the cover in which the manifold 621 and filler member625 reside. While the cover 610 may be substantially inelastic such thatthe cover 610 acts as a substantially rigid constraint, the cover 610instead may be elastic, thereby allowing some expansion of the dressingabove or below the epidermis 613 of the patient that surrounds thetissue site 601.

A fluid containment member 645 is positioned in fluid communication withthe manifold 621 and the space 628 beneath the cover 610. In oneembodiment, the fluid containment member 645 is a fluid pouch thatincludes an absorbent 629 similar to other absorbents described herein.The fluid containment member 645 may be positioned above the cover 610outside of the sealed space 628. Alternatively, the fluid containmentmember 645 may be positioned beneath the cover, and in one embodimentfluid containment member 645, or absorbent 629 therein, may be in directcontact with the manifold 621.

In the embodiment illustrated in FIG. 6, an inner space of the fillermember 625 is fluidly coupled to a positive pressure source 653. Thepressure of fluid provided by the positive pressure source 653 isregulated by a regulating valve 660. No reduced pressure source isprovided in the embodiment illustrated in FIG. 6. Instead fluid removalfrom the tissue site 601 is provided by the fluid containment member645. As the manifold 621 becomes filled with fluid, the absorbent 629 inthe fluid containment member 645 assists in drawing the fluid from themanifold 621 and into the fluid containment member 645 for storage. Themovement of the fluid is further aided by the inflation of the fillermember 625, which decreases the volume of the space 628 occupied by themanifold 621 and thus the fluid.

While no reduced pressure source is illustrated in FIG. 6, it isimportant to note that a reduced pressure source may be fluidlyconnected to the fluid containment member 645 to provide active drainageof the space 628 and the tissue site 601. Such a reduced pressure sourcemay be similar to the other reduced pressure sources described herein.

In FIG. 6, the fluid containment member 645 is fluidly connected to themanifold 621 by a pressure interface 633 positioned adjacent to orcoupled to the cover 610. The cover 610 includes an aperture 635 throughwhich the pressure interface 633 passes. A conduit 637 fluidly couplesthe therapy unit 604 (and positive pressure source 653) to the interface633. Fluid connection between the interface 633 and the filler member625 allows a fluid (i.e. a gas or liquid) to be delivered to the fillermember 625 under positive pressure such that the filler member 625 maybe inflated or expanded.

As illustrated in FIG. 6, the filling of the filler member 625 in theabsence of reduced pressure to the space 628 may result in the dressing602 expanding above the epidermis 613 of the patient that surrounds thetissue site 601. This expansion of the dressing 602 assists in applyinga biasing force, represented by arrows 672, to the tissue site 601. Theinflation of the filler member 625 beneath the cover 610 results in noreduced pressure being needed to encourage granulation. In thisparticular embodiment, fluid is removed from the dressing 602 withoutreduced pressure as well.

Referring to FIG. 7, an illustrative embodiment of a tissue treatmentsystem 700 for treating a tissue site 701 on a patient includes adressing 702 placed proximate to the tissue site 701 and a therapy unit704 fluidly coupled to the dressing 702. Tissue treatment system 700 issimilar to tissue treatment systems 100, 300, 400, 500, 600 and includesmany components that are the same as or similar to those in tissuetreatment systems 100, 300, 400, 500, 600.

Tissue treatment system 700 includes a filler member 725 that isinflated with a fluid. Unlike, some previously illustrated embodiments,the embodiment illustrated in FIG. 7 does not include a manifold.Instead, the filler member 725 includes at least onegranulation-promoting surface 727 that is brought into contact with thetissue site 701 when the filler member 725 is inflated. The fillermember 725 is constrained by a cover 710 secured to an epidermis 713 ofthe patient such that biasing forces may be applied to the tissue site701 by the granulation-promoting surface 727. The cover creates a sealedspace 728 beneath the cover in which the filler member 725 resides.While the cover 710 may be substantially inelastic such that the cover710 acts as a substantially rigid constraint, the cover 710 instead maybe elastic, thereby allowing some expansion of the dressing above orbelow the epidermis 713 of the patient that surrounds the tissue site701.

A fluid containment member 745 is positioned in fluid communication withthe space 728 beneath the cover 710. In one embodiment, the fluidcontainment member 745 is a fluid pouch that includes an absorbent 729similar to other absorbents described herein. The fluid containmentmember 745 may be positioned above the cover 710 outside of the sealedspace 728. Alternatively, the fluid containment member 745 may bepositioned beneath the cover, and in one embodiment fluid containmentmember 745, or absorbent 729 therein, may be in direct contact with thefiller member 725.

In the embodiment illustrated in FIG. 7, an inner space of the fillermember 725 is fluidly coupled to a positive pressure source 753. Thepressure of fluid provided by the positive pressure source 753 isregulated by a regulating valve 770. No reduced pressure source isprovided in the embodiment illustrated in FIG. 7. Instead fluid removalfrom the tissue site 701 is provided by the fluid containment member745. As the space 728 becomes filled with fluid, the absorbent 729 inthe fluid containment member 745 assists in drawing the fluid from thespaced 728 and into the fluid containment member 745 for storage. Themovement of the fluid is further aided by the inflation of the fillermember 725, which decreases the volume of the space 728.

While no reduced pressure source is illustrated in FIG. 7, it isimportant to note that a reduced pressure source may be fluidlyconnected to the fluid containment member 745 to provide active drainageof the space 728 and the tissue site 701. Such a reduced pressure sourcemay be similar to the other reduced pressure sources described herein.

In FIG. 7, the fluid containment member 745 is fluidly connected to thespace 728 by a pressure interface 733 positioned adjacent to or coupledto the cover 710. The cover 710 includes an aperture 735 through whichthe pressure interface 733 passes. A conduit 737 fluidly couples thetherapy unit 704 (and positive pressure source 753) to the interface733. Fluid connection between the interface 733 and the filler member725 allows a fluid (i.e. a gas or liquid) to be delivered to the fillermember 725 under positive pressure such that the filler member 725 maybe inflated or expanded.

As illustrated in FIG. 7, the filling of the filler member 725 in theabsence of reduced pressure to the space 728 may result in the dressing702 expanding above the epidermis 713 of the patient that surrounds thetissue site 701. This expansion of the dressing 702 assists in applyinga biasing force, represented by arrows 772, to the tissue site 701. Theinflation of the filler member 725 beneath the cover 710 results in noreduced pressure being needed to encourage granulation. In thisparticular embodiment, fluid is removed from the dressing 702 withoutreduced pressure as well.

Referring to FIGS. 8-10, an illustrative embodiment of a tissuetreatment system 800 for treating a tissue site 801 on a patientincludes a dressing 802 placed proximate to the tissue site 801 and atherapy unit 804 fluidly coupled to the dressing 802. The dressing 802is configured to promote the growth of new tissue at the tissue site 801and includes a wound healing apparatus 806 positioned adjacent to or, insome embodiments, in contact with the tissue site 801. The dressing 802may further include a cover or drape 810 positioned over the woundhealing apparatus 806 to secure the wound healing apparatus 806 at thetissue site 801 and to seal a space that is beneath the cover and is atleast partially occupied by the wound healing apparatus 806. In oneembodiment, the drape 810 extends beyond a perimeter of the tissue site801 and is placed either in contact with or otherwise in proximity to apatient's epidermis 813 to create a fluid seal between the drape 810 andthe epidermis 813. The drape 810 may include an adhesive 815 or bondingagent to secure the drape 810 to the epidermis 813. In one embodiment,the adhesive 815 may be used to create a seal between the drape 810 andthe epidermis 813 to prevent leakage of reduced pressure from the tissuesite 801. In another embodiment, a seal layer (not shown) such as, forexample, a hydrogel, hydrocolloid (for example as supplied by Avery or3M), silicone gel (for example as supplied by Dowcorning, Wacker, orNuSil), hot-melt glue (for example as supplied by Plasto, AdhesiveResearch, or Avery), or other material may be disposed between the drape810 and the epidermis 813 to augment or substitute for the sealingproperties of the adhesive 815.

The wound healing apparatus 806 may include a manifold 821 and a fillermember 825. In one embodiment, the wound healing apparatus 806 includesa porous foam and having a plurality of interconnected cells or poresthat act as flow channels. The porous foam may be a polyurethane,open-cell, reticulated foam such as GranuFoam® material manufactured byKinetic Concepts, Incorporated of San Antonio, Tex.

The filler member 825 of the reduced pressure apparatus 806 may beprovided to occupy additional space or volume between the tissue site801 and the cover 810 and may also be provided to better facilitate theapplication of a positive force to the tissue site 801 in order toencourage granulation and new tissue growth. In the embodimentillustrated in FIGS. 8-10, the filler member 825 is a pre-filled bladderor other container that is positioned between the tissue site 801 andthe cover 810. The filler member 825 includes at least one chamber 824sealingly enclosed by chamber walls 826. The chamber 824 retains a fluidthat in one embodiment may be a gas such as air. The pressure of thefluid within the chamber 824 may be greater than or equal to ambientpressure. If the chamber walls 826 are elastically deformed, the fluidis most likely at a pressure slightly greater than ambient pressure. Ifthe chamber walls 826 are not elastically deformed, the pressure of thefluid may be about the same as ambient.

In the embodiment illustrated in FIGS. 9 and 10, the chamber walls 826of the filler member 825 include a first wall 828 joined to a secondwall 830 to form the chamber 824. In this embodiment, the filler member825 includes a plurality of chambers 824, each chamber 824 beingconnected to an adjacent chamber at a sealing joint 832. The sealingjoint 832 is the location at which the first and second walls 828, 830are sealed together, and this sealing process may be accomplished byheat bonding, adhesive bonding, ultrasonic welding, or any other processcapable of connecting the walls 828, 830 together. The process chosen tobond the walls 828, 830 may vary depending on the material property ofthe walls 828, 830. The sealing joint 832 acts as a hinge betweenadjacent chambers 824, thereby allowing rotational movement of onechamber 824 relative to another. As an alternative to the sealing joint832 forming a hinged connection between adjacent chambers 824, aplurality of chambers 824 may be adhered or otherwise attached to aflexible membrane or substrate such that a hinged configuration isprovided between adjacent chambers 824.

Although the filler member 825 has been described as including firstwall 828 and second wall 830, it should be noted that each chamber 825may constructed from individual walls separate from the walls that formadjacent chambers. In addition, the number of walls associated with thefiller member 825 or each chamber may vary depending on the desiredshape of each chamber or the filler member. For example, a chamber thatis formed in the shape of an octahedron may include eight walls.Alternatively, a spherical chamber may only include a single wall.

The walls 828, 830 of the filler member 825 may be made from anyflexible material that is capable of maintaining a substantially sealedchamber. Examples of suitable materials may include polyurethanes,thermoplastic elastomers, silicone elastomers and other elastomericpolymers such as polyepichlorohydrin, butyls (including halogenatedforms), or polyether block amine copolymers (PEBAX), and thin flexiblefilms, such as polyolefines, copolyesters, and polyamides.

The manifold 821 and filler member 825 may work together to encouragetissue growth in the presence of a positive force or pressure. Inone-embodiment, the manifold 821 may include at least onegranulation-promoting surface 827 that is capable of contacting thetissue site 801. The granulation-promoting surface 827 is capable ofinducing micro-stresses and micro-strain at the tissue site 801 when thegranulation-promoting surface 827 contacts the tissue site 801. Forexample, if the manifold 821 is a reticulated porous foam that includesa plurality of interconnected cells formed by struts or cell walls, thestruts of the reticulated foam may be capable of inducing micro-stressesand micro-strains when the struts are pressed against or into thetissue. By sealing the manifold 821 and filler member 825 proximate thetissue site 801 with the cover 810, the presence of the filler member825 within the sealed space beneath the cover 810 assists in directing aforce on the manifold 821 at least in the direction of the tissue site801. This force is capable of generating the required micro-stresses andmicro-strains where the tissue contacts the granulation-promotingsurface 827.

In one embodiment, the cover 810 may be placed over the manifold 821 andfiller member 825 such that the filler member 825 is somewhat compressedas the cover 810 is attached to the patient. This compression of thefiller member 825 assists in amplifying the force applied to themanifold 821 and thus the tissue site 801. Although not required, thecover 810 may be formed from a material that is elastically deformed asthe cover 810 is applied. Examples of suitable cover materials mayinclude polyurethanes, thermoplastic elastomers, silicone elastomers andother elastomeric polymers such as polyepichlorohydrin, butyls(including halogenated forms), or polyether block amine copolymers(PEBAX), and thin flexible films, such as polyolefines, copolyesters,and polyamides.

In FIG. 8, the filler member 825 is positioned between a first portion834 and a second portion 836 of the manifold 821. A pressure interface833 is fluidly coupled to the wound healing apparatus 806 and the cover810. In one embodiment, the interface 833 may be positioned adjacent toor coupled to the cover 810 to provide fluid access to the wound healingapparatus 806. The cover 810 includes an aperture 835 for providingfluid access to the interface 833. A conduit 837 fluidly couples thetherapy unit 804 and the interface 833. The interface 833 is capable ofallowing reduced pressure to be delivered to the tissue site 801 when itis desired to remove fluid from the tissue site 801 under the influenceof reduced pressure.

In one embodiment, the therapy unit 804 includes a fluid containmentmember 845 in fluid communication with a reduced pressure source 851.Liquids or exudates communicated from the wound healing apparatus 806through the conduit 837 are removed from the conduit 837 and retainedwithin the containment member 845. In the embodiment illustrated in FIG.8, the fluid containment member 845 is a collection canister thatincludes a chamber for collecting fluids from the tissue site 801. Thefluid containment member 845 alternatively could be an absorbentmaterial or any other container, device, or material that is capable ofcollecting fluid.

Referring still to FIG. 8, the reduced pressure source 851 may be one ormore electrically-driven vacuum pumps. In another implementation, thereduced pressure source 851 may instead be one or more manually-actuatedor manually-charged pumps that do not require electrical power. Thereduced pressure source 851 instead may be any other type of pump, oralternatively a wall suction port or air delivery port such as thoseavailable in hospitals and other medical facilities. The reducedpressure source 851 may be housed within or used in conjunction with thetherapy unit 804, which may also contain sensors, processing units,alarm indicators, memory, databases, software, display units, and userinterfaces 861 that further facilitate the application of reducedpressure treatment to the tissue site 801. In one example,pressure-detection sensors (not shown) may be disposed at or near thereduced pressure source 851. The pressure-detection sensors may receivepressure data from the interface 833 via lumens in the conduit 837 thatare dedicated to delivering reduced pressure data to thepressure-detection sensors. The pressure-detection sensors maycommunicate with a processing unit that monitors and controls thereduced pressure that is delivered by the reduced pressure source 851.

To use the tissue treatment system 800, a caregiver places the firstportion 834 of the manifold 821 in contact with the tissue site 801 suchthat the granulation-promoting surface 827 is in contact with the tissuesite 801. The filler member 825 is then positioned above the firstportion 834, and preferably the amount of filler member 825 is adjustedto substantially fill the space that will be beneath the cover 810. Thefiller member 825 may be trimmed along the sealing joints 832 or throughthe chambers 824 to re-size the filler member 825 to an appropriatesize. In the embodiment illustrated in FIG. 8, a single-piece fillermember 825 is folded in half to more adequately fill the space.Alternatively, multiple pieces of the filler member 825 may bepositioned to substantially fill the space. In one embodiment, enough ofthe filler member 825 is added to allow the filler member 825 to besubstantially level with the epidermis 813 surrounding the tissue site801. After placement of the filler member 825, the second portion 836 ofthe manifold 821 is positioned above the filler member 825, and then thecover 810 is positioned over the second portion 836. The cover 810 issecured to the epidermis 813 surrounding the tissue site 801, and thepressure interface 833 is positioned in contact with the cover 810 andin communication with the aperture 835. The reduced pressure source 851is fluidly connected to the pressure interface 833.

As reduced pressure is applied to the space beneath the cover 810, airand other fluids removed from the space cause the cover 810 to compresstoward the tissue site 801. This compression enhances the force exertedon the tissue site 801 by the granulation-promoting surface 827, andaids in the formation of granulation tissue. As exudate and other fluidsare produced by the tissue site 801, the presence of the manifold 821below and above the filler member 825 assists in channeling the fluidsaround the filler member 825 and into the fluid containment member 845.

While the tissue treatment system 800 of FIG. 8 is described as having atwo-piece manifold system surrounding the filler member, the manifoldcould be a one-piece manifold that encases the filler member.Alternatively, as previously described in relation to FIG. 7, themanifold may be omitted and a filler member used that includes agranulation-promoting surface. Similarly, many fluid handling andstorage alternatives are possible for the tissue treatment system 800.In a similar manner to those system described previously herein, thecollection canister that is remotely located from the tissue site mayinstead be an absorbent material. The absorbent material may be providedas a layer of the dressing as shown in FIG. 4, or may be locatedexternal to the dressing as shown in FIGS. 5-7.

The multi-chambered filler member 825 described herein is pre-inflatedand sealed such that the fluid within each chamber is trapped. While itmay be preferred in the embodiment illustrated in FIG. 8 to use apre-inflated filler member, it should be noted that the fillable andexpandable filler members described herein and illustrated in FIGS. 1-7may also be multi-chambered similar to filler member 810. In otherwords, it is contemplated that a multi-chambered filler member could beconnected to a positive pressure source such that the delivery of fluidto the chambers under positive pressure may be controlled followingplacement of the filler member in proximity to the tissue site.

The tissue treatment systems described herein allow the use of a reducedpressure treatment protocol that uses less reduced pressure (i.e. higherabsolute pressures) than traditional protocols. By increasing thegranulation-inducing microstrains and microstresses using positiveforces and positive pressures, the amount of reduced pressure needed fortreatment is greatly reduced. In fact, testing has shown that a pressureof −75 mm Hg, coupled with a positive pressure provided by either aninflatable or pre-inflated bladder, achieves an interface-pressureequivalent (the pressure measured at the interface of thegranulation-promoting surface and the tissue site) of −125 mm Hg.

The systems described herein have the ability to manage fluid andinterfacial pressures independently. This is particularly useful inintermittent mode where a caregiver can maintain constant fluidmanagement (e.g. removal) while alternating the application ofmicrostrain on the tissue site. This also may be more beneficial forpain management in that the effect of transient strains my be reduced bymanaging the application of the positive and negative pressuresindependently. Finally, these methods result in a simpler system withlower energy requirements.

The separation of fluid removal and microstrain induction may also bebeneficial when it is not desirable to draw together the perimeter of awound or tissue site. In traditional reduced pressure treatment, theapplication of higher amounts of reduced pressure to dressings promotedclosure by primary intention by drawing together the edges or perimeterof the wound. However, this is not always advantageous, especially whenthe wound is to a joint or articulation point. In these areas ofarticulation, the contraction of tissue may lead to impinged movement,which may cause secondary problems for the patient or the need forpainful physiotherapy to break down these tissue formations to restoremovement. It may beneficial in these circumstances to heal the wound bysecondary or tertiary (delayed primary) intention as is commonly used inreconstructive surgery. The tissue treatment systems described hereinallow the benefit of reduced pressure treatment to be applied to awound, yet the inflatable or pre-inflated bladder resists the collapseof the wound perimeter inward and thus constriction of the surroundingtissue.

While many of the systems described herein have been illustrated in usewith tissue sites or wounds that are at or near the epidermis of apatient, the systems and methods may similarly be used to treatsubcutaneous tissue sites, tunnel wounds, or other undermined areas oftissue. With these types of wounds or tissue sites, accessibility may belimited, thereby making placement and removal of traditional foams andmanifolds more difficult. The ability of the bladders described hereinto be deflated upon installation and removal would ease the process ofapplying treatment to these difficult-to-access wounds and tissue sites.

While many of the tissue treatment systems described herein include theuse of negative pressure in conjunction with the application of apositive pressure or force, the use of absorbent materials for passivefluid removal may assist in completely eliminating the need for reducedpressure. In such a system, fluid may be removed passively from thewound and stored in an absorbent layer, while a positive pressure orforce is used to create microstrains at the tissue site.

While many of the tissue treatment systems described herein may includea separate cover member or drape to secure and seal the filler memberand any granulation-promoting surfaces or material at the tissue site,the cover member or drape may be integrally combined with the fillermember to secure or seal these components at the tissue site. Forexample, in one embodiment, the cover member may be an integral portionof the filler member that is capable of being secured to an epidermis ofthe patient such that the interior chamber of the filler member and anygranulation-promoting material is sealed within a space beneath thecover member at the tissue site.

It should be apparent from the foregoing that an invention havingsignificant advantages has been provided. While the invention is shownin only a few of its forms, it is not just limited but is susceptible tovarious changes and modifications without departing from the spiritthereof.

We claim:
 1. A wound healing system for promoting healing of a wound ofa patient, the system comprising: a positive pressure source; a reducedpressure source; a porous foam configured to be positioned in contactwith the wound, the porous foam having a plurality of flow channels influid communication with the reduced pressure source; a filler member influid communication with the positive pressure source, wherein thefiller member is embedded within and surrounded by the porous foam; acover member configured to be positioned over the filler member and tocreate a sealed space; and a fluid containment member configured to bepositioned outside of the sealed space.
 2. The wound healing system ofclaim 1, wherein the positive pressure source and the negative pressuresource are separate pumps.
 3. The wound healing system of claim 2,wherein at least one of the separate pumps is a piezoelectric-actuatedpump.
 4. The wound healing system of claim 1, wherein: positive pressureis supplied by an outlet of a pump to an interior chamber of the fillermember; and negative pressure is supplied by an inlet of the pump to aspace beneath the cover member surrounding the filler member.
 5. Thewound healing system of claim 1, wherein the porous foam is apolyurethane, open-cell, reticulated foam.
 6. The wound healing systemof claim 1, wherein: the porous foam includes at least a first portionand a second portion; the first portion is positioned between the fillermember and the wound; and the second portion is positioned between thefiller member and the cover member.
 7. The wound healing system of claim1, wherein the porous foam comprises a granulation-promoting surface incontact with the wound to induce microstrain at the wound when thefiller member is expanded.
 8. The wound healing system of claim 1,wherein the fluid containment member is positioned between the reducedpressure source and the wound to collect exudate from the wound.
 9. Thewound healing system of claim 8, wherein the fluid containment member isa fluid collection canister.
 10. The wound healing system of claim 8,wherein the fluid containment member is an absorbent layer positionedbeneath the cover member.
 11. The wound healing system of claim 8,wherein the fluid containment member is an absorbent-containing fluidpouch positioned outside of the cover member.
 12. A wound healing systemfor promoting healing of a wound, the system comprising: a positivepressure source; a manifold comprising a granulating-promoting surfaceconfigured to be positioned in contact with the wound; a filler memberoperably associated with the manifold, the filler member comprising anexpandable wall defining an interior chamber in fluid communication withthe positive pressure source, wherein the filler member is embeddedwithin and surrounded by the manifold; a cover member configured to bepositioned over the filler member to secure the filler member at thewound and to create a sealed space capable of maintaining a pressure;and an absorbent-containing fluid pouch configured to be positionedoutside of the sealed space.
 13. The wound healing system of claim 12,wherein the filler member includes a granulation-promoting surface incontact with the wound to induce microstrain at the wound when thefiller member is expanded.
 14. The wound healing system of claim 12,wherein the manifold is a polyurethane, open-cell, reticulated foam. 15.The wound healing system of claim 12, wherein: the manifold includes atleast a first portion and a second portion; the first portion ispositioned between the filler member and the wound; and the secondportion is positioned between the filler member and the cover member.16. The wound healing system of claim 12, wherein the absorbentcontaining fluid pouch is positioned outside of the cover member and influid communication with the sealed space to collect exudate from thewound.
 17. The wound healing system of claim 12, wherein external fluidsare not supplied to the wound.
 18. A wound healing system for promotinghealing of a wound of a patient, the system comprising: a positivepressure source; a reduced pressure source; a porous foam configured tobe positioned in contact with the wound, the porous foam having aplurality of flow channels in fluid communication with the reducedpressure source; a filler member having a flexible wall defining aninterior chamber, the interior chamber being in fluid communication withthe positive pressure source, the filler member further comprising acover member capable of sealing the porous foam and the interior chamberwithin a space beneath the cover member at the wound, wherein the fillermember is embedded within and surrounded by the porous foam; and a fluidcontainment member configured to be positioned outside of the sealedspace beneath the cover member and in fluid communication therewith forcollecting exudate from the wound.